Please tell me how I can check to see who filled out my form?

How do I know if someone has filled out my form after I sent the link>

You can setup email notifications: https://www.jotform.com/help/25-Setting-Up-Email-Notifications 

Also, you can login to your account, and check the submissions page: https://www.jotform.com/help/269-How-to-View-Form-Submissions 

Let us know if you need more help.